Voltage surge protectors currently draining to ground lightning surges and that are installed in transmission lines of medium and high voltage are generally formed by a plurality of varistors connected by way of a column, an upper electrode connected to the upper edge of the column of varistors, a lower electrode connected to the lower edge of the column of varistors, an insulating housing surrounding the column of varistors, a fiberglass cover surrounding the insulating housing and a weatherproof protective cover provided with barriers mounted on the fiberglass cover. Some examples of patent documents that describe the configuration of this type of devices are Japanese Patent Publication JP-61151913 and the publication of Japanese Utility Model JP-196739.
Under this basic structure of this type of voltage surge protector, upon receiving a lightning surge, high pressure is generated inside the device which causes the explosion of the same, and therefore its fragmentation and dangerous launching of the fragments out of the device.
According the test standard IEC 60099-4 (short circuit test), these devices may fail imminently upon receiving a lightning stroke but its structure must avoid a dangerous explosion and release of fragments in the form of projectiles. Therefore, mechanisms are implemented to release the pressure generated by a surge in the protective devices consisting of the placement of grooves or holes in the wall of the insulating housing, as described in Japanese patent application publication JP61151913, in U.S. Pat. No. 5,113,306, and in published European patent application EP-0493134. However, these grooves or holes do not fully prevent this problem, as they are axially arranged along the wall of the insulating housing in a straight line setting, that, although decreasing the outward launching of fragments during the explosion, cause the protective device to split in half or more fragments that can still be launched outward as projectiles.
Therefore, the prior art continues to present the problems as described above, so there is still a need to provide a voltage surge protector that during a lightning stroke explodes without throwing fragments outward and therefore fully complies with testing standard IEC-60099-4.